Symbol display apparatus



Jan. 10, 1967 R. A. KosTER 3,298,013

SYMBOL DISPLAY APPARATUS Filed July 1, 1965 2 Sheets-Sheet l 'iowlwih- 55' IA' 2\ 28' UNBLANKNG WM5 Ig. 5(5) M mmm 1Hfmm T Hmm 1 m 1 u l /H \2CJ X SYMBOL Pom-mom DEFLECUON @ENEQATOR AMPMHER 1 )22. r@A ,l |O

y SYMBOLPOSWQN DEPLECUON CRT GENERATOR AMPLu-am ORGlN SYNCHRONUJNC: Y f\ xe Emsa ,|12 DCQL SYMBOL n UNBLAN\ \NG H4 CAR R l SGE START I NVENTOR. @51239 g3g-E /PoE/QT A. KOTE/Q BY I Jly. 5 m 774.

A Foren/Ey Jam l0, 1967 R. A. KosTER SYMBOL DISPLAY APPARATUS 2 Sheets-Sheet z Filed July 1, 1953 @ma oz 65mm dub/ DOO O OP m@ INVENTQR. ROBERTA. KOTgR r BY i AHORA/y United States Patent O 3,298,913 SYMBOL DISPLAY APPARATUS Robert A. Koster, Canoga Park, Los Angeles, Calif., as-

signor, by mesne assignments, to The Bunker-Ramo Corporation, Stamford, Conn., a corporation of Delaware Filed .luly 1, 1963, Ser. No. 291,956 11 Claims. (Cl. 340-324) This invention relates to symbol display apparatus and, more particularly, to apparatus for accepting digitally coded input signals `representing various symbols and producing those symbols on a display device.

Most people are familiar with outdoor signs in which a variety of symbols are presented by illuminating ydifferent combinations of electric light bulbs arranged in a matrix. Such signs are found in advertising displays, in Scoreboards on athletic fields, in time and temperature displays, and in a variety of other applications. A similar technique for generating symbols of illuminating predetermined -combinations of points arranged in a matrix has now been applied to high-speed displaying of inforrnation derived from a computer.

In the art of Ihigh-speed data display, symbols are usually generated on a phosphor-coated face of a cathode ray tube by an electron beam within the tube. Voltages are provided to sequentially position the beam at the various locations on the face of the tube Where it is desired to display symbols. This action is analogous to typing a page of symbols on a typewriter. While the beam is at each of the locations at which it is ydesired to display a symbol, additional voltages are provided to cause the beam to scan a matrix of points and to cause predetermined combinations of those points on the phosphorcoated face of the tube to glow to provide visible symbols. That portion of the display apparatus which causes the electron beam to scan the matrix of points and to turn the beam on and off to cause only predetermined combinations of points to emit visible light is known as a symbol generator.

The input to a symbol generator is usually in the form of six bit digitally coded signals, which must be con- Verted to signals of the proper type for generating the symbol display on the face of the cathode ray tube. If a six bit input code is used, it may involve up to sixtyfour different combinations, each of which represents a different symbol. If `it is desired to create each symbol on, for example, a x 7 matrix of points on the cathode ray tube face, it is necessary that each of the sixty-four different input signals be converted to a diiferent thirtyve bit output signal, with each bit of the output signal representing a different one of the thirty-live points on the 5 x 7 matrix. This involves the provision of six bit to thirty-tive bit binary conversion circuitry in the symbol generator.

One type of conversion apparatus that has been utilized for this purpose includes la memory device having stored within it the various possible output signals or Words. Receipt of a digitally coded input signal initiates a search of the memory device to lind the desired output word. Examples of such memory devices are rotating magnetic drums or discs with bits permanently recorded on a track and sensed by a magnetic read head. Another example of such a device is a rotating drum or disc with bits marked on it so that they can be sensed optically by a photocell.

A disadvantage of such rotating memory devices, as heretofore used, is that all of the bits of an output word are recorded sequentially and adjacent each other on the recorded track of the device. The output words are sequentially recorded around the track. This means that each output word is recorded on the memory device at a ice dilerent `distance from a given reference point on the recorded track. Because of this, there is a variable time delay introduced into the apparatus that must be removed before the output signal can be utilized to actuate a display device. Furthermore, the bits of each desired output word all become available within a short period of time and there is then a relatively long, and variable, period of time before the bits of the next output word are available. The display device which uses these bits is less expensive if it is designed to accept the bits in the output words in a smooth :sequence rather than in bursts. For these reasons, it has been necessary to provide storage apparatus such as a butler register to receive.` the desired output Word from the memory device and store it until it is read out at the proper time and at a suitable speed for the display device to accept the word. The present invention provides symbol display apparatus which does not involve the use of a buffer between its memory device and display device, which provides symbol generating signals to the display device at a rate of speed at which the device can accept them, and which synchronizes those signals with symbol positioning signals also provided to the display device.

Broadly speaking, the present invention is based on the concept that all of the bits of a multibit output word to be supplied to a display device do not need to be -recorded sequentially on a moving memory medium without gaps between the bits. In fact, numerous advantages are attained if the bits comprising each output word are so spaced apart on the memory medium that they may be supplied to the display device at a rate `at which it can accept them. The present invention contemplates dividing the memory medium into a plurality of sectors at least equal in number to the number of bits in each output word. Each sector is of such size that it is capable of storing a number of bits at least equal in number to the number of output words. One bit from each of the output words is stored in each sector with those bits forming each output word being stored in like places in all of the sectors. For example, if there are thirty-live bits in each output Word, the storage medium may be divided into thirty-tive sectors and, if there are sixty-four possible combinations of those output bits, each sector would be capable of vstoring sixty-four bits. The first sector would contain the iirst bits of each of the sixty-four words, the second sector would contain the second bits of the sixtyfour words in the same sequence as in the first sector, and so on until the thirty-iifth sector contains the thirty-fifth bits of the sixty-four words. Thus, it is seen that every sixty-fourth bit recorded on the memory medium is part of the same thirty-live bit output word. Readout means are provided which are selectively responsive: to the sixtyfour different input signals for sequentially reading out from the sectors of the storage medium all bits stored in like places in the sectors Various synchronizing and clock pulses are also stored on the recording medium. When the display device utilized is, for example, a cathode ray tube, the synchronizing pulses control its electron beam sweep, and the symbol generating output words control blanking and unblanking of the electron beam to generate symbols on the tube face.

The invention, together with further features and advantages, will be better understood from the following description, taken in conjunction with the accompanying drawings, in which:

FIGS. l and 2 are diagrams useful in understanding the generation of symbols from a matrix arrangement of elect-ric light bulbs;

FIGS. 3a, 3b, 4m and 4b are diagrams useful in understanding the generation of symbols on the face of a cathode ray tube on a matrix of points;

FIG. is a block diagram of symobl display apparatus embodying the invention; and

FIG. 6 is a block diagram of the system of FIG. 5, but showing a symbol generator in greater detail and also showing a memory device in diagrammatic perspective view.

FIGS. 1 and 2 are useful in understanding the generation of various symbols on, for example, a 5 x 7 matrix arrangement of electric light bulbs. If the bulbs .are `arranged substantially as shown in the figures and are nurnbered `from 1 through 35, it is readily seen that if bulbs numbered 1, 7, 8, 9, 10, 11, 12, 13, 14, 15, 21, 22, 28, 30, 31, 32, 33 and 34 are illuminated and all others remain dark, a letter D is formed (FIG. 1). Similarly, as seen in FIG. 2, if bulbs numbered 1, 2, 3, 4, 5, 6, 7, 11, 17, 18, 19, 23, 27, 29 and 35 are illuminated, a letter K is formed. Thus, it is apparent that by illuminating dif- -ferent ones of the thirty-five electric light bulbs, both alphabetical and numerical symbols may be formed from a matrix of only thirty-live bulbs. Although the generation of symbols by illuminating various combinations of light bulbs arranged on a matrix is quite useful for outdoor displays and signs, it is obviously unsuitable for displaying text in a format similar to typewritten or printed pages. However, analogous techniques can be used. For example, the matrix of light bulbs shown in FIGS. 1 and 2 may be replaced by a cathode ray tube having a phosphor-coated face over which an electron beam is caused to move. If the intensity of the beam is made sufficiently great at predetermined points, which is known as unblanking the beam, the phosphor on the face of the tube may be caused to glow at those points and form visible symbols. FIGS. 3 and 4 illustrate this analogous technique.

If an electron beam on a cathode ray tube can be made to scan over a matrix of points on the phosphorcoated face of the cathode ray tube and can be unblanked at certain of those points, visible symbols can be generated on the face of the tube. A possible scanning pattern is shown in FIG. 3 (a) -where an electron beam scans in zigzag 'fashion over a 5 x 7 matrix of points and is un- -blanked at certain of the points. As shown, if the beam is unblanked at points numbered 1', 7', 8', 9', 10', 11', 12', 13', 14', 15', 21', 22', 28', 30', 31', 33' and 34', a letter D is developed. FIG. 3(b) illustrates as ia function of time the unblanking pulses that are applied to the cathode ray tube to cause the phosphor to emit light in the pattern shown in FIG. 3(a). Obviously, the sweep of the electron beam across the face of the tube and the unblanking pulses applied to the tube must be synchronized in order to generate a meaningful symbol.

FIGS. 4(a) and 4(b) are similar to FIGS. 3(a) and 3(b), respectively, but illustrate the unblanking pattern necessary to form a letter K. As can be seen from a comparison of FIGS. 3(1)) and 4(1)), the time sequence of unblanking pulses is quite different for generating the two letters. Each symbol to be generated has a unique sequence of unblanking pulses which is like that of no other symbol.

Having looked at a fundamental method of generating symbols on the face of a cathode ray tube, let us now consider apparatus embodying the invention for performing that function. Throughout the following description and for purposes of illustration only, it is assumed that the apparatus of the invention receives a six bit binary input signal and converts that signal into a thirty-tive bit output signal to create a symbol on a 5 x 7 matrix of points. It is pointed out, however, that the invention is in no way limited to the use of an input signal having a particular number of bits or to the production of symbols on any particular size matrix of points. Apparatus embodying the invention may be easily modified to operate on various types of input signals and to produce symbols on any desired form of matrix. It is understood that as used herein the term bit is used to describe a signal, which may be in one of two states, in the usual computer sense.

FIG. 5 yshows a simplified block diagram of apparatus embodying the invention for producing symbols on a cathode ray tube 110. The tube is of conventional type having a phosphor-coated face and containing an electron gun for producing a beam of electrons. The beam of electrons is caused to impinge on the phosphorcoated face of the tube at various points under the control of deflection circuitry and the beam is blanked and unblanked through a conventional unblanking circuit 112, such as a video -amplier, to effectively write symbols on the face of the tube.

The unblanking circuit 112 is controlled by a symbol generator 114 to cause symbols to appear on the Vface of the cathode ray tube in the manner previously described with reference to FIGS. 3 and 4. The symbol generator 114 is provided lwith input signals from a digital data source 116, such as a computer output register. In the present illustration, the input signal provided to the symbol generator 114 comprises six binary bits which are fed in parallel to the symbol generator. However, it is again noted that the invention is not limited to the use of this particular input signal. y

The symbol generator 114 serves not only to control the blanking and unblanking of the electron beam of the cathode ray tube to generate symbols, but also to synchronize positioning of the electron beam with symbol generation. After each symbol is generated, a pulse called the origin synchronizing pulse is provided to an X symbol position generator 118. The X symbol position generator 118 provides voltages, which may be amplified by a deilection amplier 121) and supplied to the deflection circuitry of the cathode ray tube 110 to position its beam in the X or horizontal direction. Each time that an origin synchronizing pulse is received `from the symbol generator, the X-symbol position generator 118 causes the electron beam of theA cathode ray tube to be moved horizontally by one space to the proper position for the next symbol to be generated; these positions may be thought of as primary positions. After a predetermined number of pulses have been received, which number corresponds to the number of primary positions in a horizontal line at which it is desired to generate symbols, the X symbol position generator 118 sends `a pulse to a Y symbol position generator 122. The Y symbol position generator 122 serves to position the cathode ray tube beam in the Y or vertical direction. Each time that .it receives a pulse from the X symbol position generator 118, indicating that a line of symbols ha-s been generated, the Y symbol position generator provides v-oltages through a deflection amplifier 124 to the lcathode ray tube 110 to cause its beam to move downwardly to another position where another line of symbols may be generated.

In accord with the usual practice in the art, carriage return pulses and start page pulses are 4supplied to the symbol position generators from the digital data source. The former pulses are provided to the X symbol position generator 118 at the end of each line of symbols and cause the generator to reset itselft-o start a new line. Similarly, start page pulses are supplied to both X and Y symbol position generators 118 and 122 to cause them to reset themselves to start a new page.

Each of the X and Y symbol position generators 118 and 122 may comprise a digital counter and a digital-toanalog converter to provide the deiiection voltages for the cathode ray tube. Both the counters and the 'converters may be of conventional types as well known in the art. If, for example, it is desired to provide thirty-two symbols in each horizontal line and thirty-two lines in one raster, the digital counters may each comprise ve ip-tlop circuits whose output-s are provided to the digitalto-analog converters. In the present embodiment, the outputs of both the X and Y symbol position generators are not smoothly rising sawtooth voltages, but rather are of the staircase type. This permits a symbol to be generated in `one position and, after it is generated, the electron beam of the cathode ray tube is quickly moved to the next position. Alternatively, smoothly rising sawn tooth voltages may be used. This will cause the symbols to be tilted slightly, which may be desirable in some applications.

As will later be explained in more detail, the symbol generator 114 also provides deection voltages tothe amplifiers 1Z0 and 124. Those voltages are utilized to cause the electron beam in the cathode ray tube to scan 1n the manner shown by FIGS. 3(a) and 4(a) in generating the various symbols.

FIG. 6 also shows the apparatus of FIG. 5, but shows the symbol generator 114 in considerably greater detail. As was previously stated, it is assumed for purposes of illustration that each symbol is to be generated on a 5 x 7 matrix of points (secondary positions) on the cathode ray tube face. Thus, the unblanking circuit 112 requires that thirty-five binary bits of information be provided to it serially from the symbol generator 114 for each symbol to be generated. With a six bit input word to the signal generator, the six bit input word having up to sixty-four different possible combinations, the symbol generator must be capable of providing up to sixty-four different cornbinations of thirty-live bit output Words. Each of the thirty-five different output word combinations is predetermined in accordance with the various symbols to be generated, in a manner similar to that described with reference to FIGS. 3 and 4.

The symbol generator 114 includes memory or storage means such as a rotatable magnetic drum 130. As previously mentioned, however, numerous other memory devices are suitable, such as rotating discs or tape loops. Furthermore, the invention is not limited to the use of magnetic recording, and other techniques, such as optical recording, may be utilized. It is necessary only that there be a capability for relative motion between the recording medium and the means for reading the recorded data.

The drum 130 has four recording tracks 131m, 1301i, 130C and 13M thereon with conventional magnetic pickup heads 131a, 13117, 131C and 131d, respectively, located to read information previously recorded on the tracks. It is pointed out that the memory drum 130` need not be utilized only for the symbol generator. It is one of the advantages of the present invention that the symbol generator requires only four recording tracks on a memory device which can also be used for other purposes in equipment with which the apparatus of the invention may be operating.

The recording track 130:1 on the drum is divided into a number M of sectors equal to the number of bits in the output words from the symbol generator, in this case, thirty-five. Each of the thirty-five sectors must be capable of storing a number of bits at least equal to the number N of different input and output words, in this case, sixtyfour. One bit from each of the sixty-four different output words is stored in each sector, with those bits forming each output word stored in like places in all of the sectors with sequential bits of each output word separated from each other by (N-1) other bits. More specifically, the first bit of the first output Word is stored in a first position in the first sector, the first bit of the second word is stored in a second position, the first bit of the third word is stored in a third position, and so on, until the first sector contains the first bit information of each of the possible sixty-four output4 words. In a similar manner, the second sector stores the second bit information for each of the sixty-four output words in the same order as they are stored in the rst sector. One bit from each of the sixty-four output words is stored in each of the thirtyefve sectors with the bits forming each word stored in like places in all of the sectors. Thus, by reading the information stored at the same position in each of the thirty-five sectors, a thirty-five bit output Word may be obtained which corresponds to one of the sixty-four input words.

In order to synchronize the reading of the output words with the deflection of the cathode ray tube beam, various other pulses are provided in tracks b, 130e and 130d. Track 130b has recorded thereon thirty-five sector synchronizing pulses (SSP), each of `which corresponds in position to the vbeginning of one of the sectors on track 131m. The track 130C contains a single pulse, called the origin synchronizing pulse (OSP), which corresponds in position to the beginning of the first sector on track 13tla. The track 13051 contains clock pulses (CP), which correspond in position to the information pulses recorded on track 130a. The track 130e could be eliminated by coding the information on one of the other tracks. For example, a pair of adjacent pulses on track 130k at one location can be decoded by digital logic to produce the origin synchronizing pulse.

The selection of a particular thirty-five bit output word to be read from the track 131m is made with a six bit counter 134 which counts in binary fashion from 63 to 0. This counter receives the six bit input signal from the data source 116. When actuated by the origin synchronizing pulse from the track 130C, whose position corresponds in time to the beginning of the first sector on the track 130a, the counter starts to count down from the number set into it by the six bit input word. Clock pulses from the track 13M actuate the counter 134, which counts down one number for each clock pulse received. When the count has reached 0, all of the counters output signals are Os and the next count takes the counter to 63 from which it continues to count down. The Os may be changed to ls by means of inverters (not shown) or complementary signals from the counter 134 may be used and passed to an AND gate 138. When all of the input signals to the AND gate are ls, a 1 is produced by the AND gate, which indicates that the desired bit to be read from track 13% is now under the read head 132er.

The output of AND gate 138 is connected as one input to another AND gate 14@ whose other input is from the read head 13211. AND gate 140 operates to pass information received from the read head 132a only when the counter 134 has counted down to 0. As previously pointed out, the length of time required for the counter 134 to reach 0 after the start of each sector on the track 130a depends on the six bit input signal from the data source 116 which sets the counter for each symbol to be generated. Although information is continuously supplied to the AND gate 140 from the read head 132a, it is passed by the gate only when the counter 134 has counted down to 0, which occurs thirty-five times for each rotation of the drum 130. Thus, it is apparent that if the input signal to the counter sets it at, for example, 5, the bits stored in the fifth positions of all sectors will be serially passed by the AND gate 140. In this manner, a thirtyfive bit output word is constructed.

There is a variable time delay `between the time the origin synchronizing pulse on track 132e` passes under its read head and the time a selected bit from track 130a, as determined by the action of the counter 134, is read. Also, there are similar time delays between the time the sector synchronizing pulses on track 132b and selected bits on track 132a pass under their respective read heads. Because the origin synchronizing pulse and the sector synchronizing pulses are utilized to control the deflection of the cathode ray tube beam, such variable time delays would cause jitter and other difficulties in the generated symbols. Therefore, a one bit memory 144, such as `a Hip-flop circuit, is provided to store the information from each sector of track 130a appearing at the output of AND gate 140 until that sector has completely passed under its read head. When a sector synchronizing pulse is applied to the one bit memory 144, the information contained in the memory is supplied as one input to an AND gate 146 and the memory 144 is reset. The sector synchronizing pulse is also supplied as a second input of the AND gate 146, so that an output may be provided from the gate at thirty-five uniformly spaced times for each revolution of the memory drum130.

The thirty-five bits comprising a one word output signal from AND gate 146, which actuate the unblanking circuit 112, must be synchronized with the position of the cathode ray tube beam on the thirty-live point matrix. Therefore, the origin synchronizing pulses :and the sector synchronizing pulses are provided to a Y bit position generator 148, which may be generally similar to the symbol position generators previously described. The Y bit position generator serves to provide staircase voltages to the deflection amplifier 124 and hence to the deflection circuitry .of the cathode ray tube 110 to position its beam in the Y or vertical direction on the desired points of the matrix. The Y bit position generator 148 may be initially actuated at the beginning of each symbol generation period by the origin synchronizing pulse received along with a sector synchronizing pulse, and thereafter each sector synchronizing pulse received causes the electron beam of the cathode ray tube to be moved vertically from point to point on the matrix until a predetermined number of pulses have been received. In the present case, when seven sector synchronizing pulses have been received, the digital counter contained in the generator resets itself and a pulse is sent to an X bit position generator 150. The X bit position generator is similar to the symbol position generators previously discussed, and is actuated at the beginning of each symbol generation period by the origin synchronizing pulse. Each time the X bit position generator 150 receives a pulse from the generator 148, it causes the electron beam of the cathode ray tube to be moved horizontally so that the Y bit position generator 148 can cause the electron beam to move along another column of points of the matrix. After five pulses have been received by the generator 150 from the generator 148, the drum 130 has made one complete revolution and another origin synchronizing pulse causes the generators 148 and 150 to be reset. The electron beam of the cathode ray tube is now repositioned to start generation of another symbol. Thus, the X and Y bit position generators 148 and 150 cause the beam of the cathode ray tube to move over the face of the tube in a manner very similar to that shown by FIGS. 3(a) and 4(a).

It will be apparent to one skilled in the art that the apparatus of the invention may easily be adapted to accept other than six bit input signals and to form symbols on other than a 5 x 7 matrix of points. For example, if it is desired to have ve bit input signals, the counter 134 may be modified so that it counts from 31 to 0 rather than from 63 to 0. Similarly, if it is desired to generate symbols on a 6 x 8 matrix rather than on :a 5 x 7 matrix, the recording track 130a would be divided into forty-eight sectors rather than thirty-five; the Y and X bit position generators 148 and 150 would be modified to provide eight-step and sixstep output voltages, respectively, rather than seven-step and live-step.

It is now apparent that the invention provides a symbol display apparatus that eliminates the need for large buffers, and in which signals are provided to a display device at a rate at which it can accept them. It requires the use of only four memory tracks of a memory device that may have hundreds of other tracks being used for other storage and retrieval purposes. The electronic circuitry embodied in the system is relatively simple and it is believed that all elements are well known to one skilled in the art.

Although :an embodiment of the invention has been shown and described, it will be apparent to one skilled in the art that many changes and modifications may be made without departing from the true scope and spirit of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In symbol display apparatus for generating selected symbols on a face of a cathode ray tube wherein an unblanking circuit controls impingement of an electron beam on said face as the beam is deected thereacross in a scanning pattern,

a memory device having bits of a binary-coded word stored in uniformly spaced positions along a storage and retrieval path therein, bits of other words being interlaced between the bits of said word;

means for reading 4out the bits of said word from said memory device over a time interval determined by said scanning pattern of said electron beam over the face of s-aid tube; and

means for actuating said unblanking circuit of said tube with the readout bits at such time intervals that each of said readout bits determines a blanking and unblanking state of said beam at different predetermined positions on said tube face.

2. A symbol display apparatus for converting an input code into a code of signals for displaying symbols, comprising:

a memory device comprising a plurality of M sectors, where M is the number of bits identifying a symbol,

each sector having N bit storage positions, where N is the number of possible symbols that may be generated,

bits of each of the symbols being stored in said memory device and interlaced with bits of other symbols so that bits N positions apart represent one of said symbols;

means for reading out of said memory device, in a predetermined readout time interval, M bits representing a symbol;

a cathode ray tube having a face and an electron beam that scans a predetermined portion of said face in vertical and horizontal directions in a scanning time interval substantially equal to the memory readout time interval; and

means synchronizing the scan of said electron beam with the readout of said memory device so that bits from each of said sectors relate to different predetermined beam positions on said portion Lof the face of said tube.

3. A symbol display apparatus for converting an input code into a code of signals for displaying symbols, comprising:

a memory device comprising a plurality of M sectors, where M is the number of bits needed to write a word which identifies a symbol, l

each sector having N bit storage positions, where N is the number of possible words` from which symbols are to be generated,

the bits of each of said words being stored in said memory device and interlaced with bits of other words so that bits N positions apart from one of said words,

each sector having 1a sector synchronization pulse recorded in a position corresponding to the beginning of said sector;

means for reading from said memory device in a predetermined time interval, M bits of 1a word;

a cathode ray tube having a face and an electron beam that scans a predetermined portion of said face in vertical and horizontal directions in a scanning time interval substantially equal to the memory readout time interval; and

synchronizing means for synchronizing the scan of said electron beam with the readout of said memory device so that bits from each of said sectors relate to different predetermined beam positions on said portion of the face of said tube,

said synchronizing means comprising a counter means triggered by said sector synchronization pulses for controlling scanning of said electron beam in a synchronization with said memory readout.

3,298,013 9 1t) 4. A symbol display apparatus for converting input the pattern repeating itself with each origin synchrocodes to displayed symbols corresponding thereto comnization pulse being sensed. prising: 6. A symbol display apparatus for converting input a memory device comprising a plurality of M sectors, codes to displayed symbols corresponding thereto com- M being the number of bits of information representprising:

ing each of said symbols,

each sector storing N bits of information, N being the number of symbols to be generated,

the bits of information of said symbols being stored recorded in a position corresponding to the beginning of said rst sector;

means for reading from said memory device in a predetermined time interval, M bits of information repa memory device comprising a plurality of M sectors,

M being the number of bits of information representing each of said symbols,

each sector storing N bits of information, N being the in said memory device so that all bits representing 10 number of symbols to be generated, each symbol are stored (N-l) positions apart from the bits of information of said symbols being stored in one another, Said memory device so that all bits representing each each sector having a sector synchronization pulse resymbol are stored (N-l) positions apart from one corded in a position corresponding to the beginning another, of said sector, each sector having a sector synchronization pulse rethe first sector having an origin synchronization pulse corded in a position corresponding to the beginning recorded in a position corresponding to the beginof said sector, ning of said first sector; the first sector having an origin synchronization pulse means for reading from said memory device in a prerecorded in a position corresponding to the beginning determined time interval, M bits of information reP- of said rst sector; regaining one Symbol; means for reading from said memory device, in a a cathode ray tube having a face and an electron beam Predeterinined time interyai, M bitS 'of information that scans a predetermined portion of said face in rePreSenting one Syinboi; vertical and horizontal directions in a scanning time `a Cathode ray 'tube having a face Vand an electron beam interval substantially equal to said predetermined for diSPiaying Said SyrnboiS on Said face at Predetertime interval; and mined primary positions; synchronizing means responsive to said sector synchro- Syniboi PoSition generating ineanS for deiieeting Said nization pulses and to said origin synchronization eieetron beain to Said Primary PoSitionS, pulse for synchronizing the scan of said electron Said Syniboi PoSition generating -irieanS being energized -beam with reading from said memory device so that by Said origin Synchronization PuiSe to defieet Said bits from each of said sectors determine blanking or bearn to another Primary Position in reSPonSe to eaeil unblanking of said beam at different predetermined origin 'Synchronization PuiSe reeeiVed thereby; and beam positions Onsaid portion ,of the face of Said synchronizing means for synchronizing the scan of said tube' electron beam with each origin synchronization pulse 5. A symbol display apparatus for converting input aud With the Sector SyneiironiZation PuiSeS S0 that codes to displayed symbols corresponding thereto combits .of information from each of Said SeCtorS repre' prising: senting a single symbol determine blanking or una memory device comprising a plurality of M sectors, biaiikiug of Said bearn at different predetermined M being the number of bits of information repre- Secondary beam positions associated with said prisenting each of said symbols, 40 mary PoSitioI1-of the face of Said' tube, each sector storing N bits of information, N being the Saidyueiironiliii means eonipriSing Counting IneanS number of Symbols to be generated, triggered by said origin .synchronization pulse and the bits of information of said symbols being stored Said .Sector Synchronization PuiSeS for ContrOlling in said memory device so that all bits representing Scanning. of Said eieetroii beam in a predetermined each symbol are stored (N-l) positions apart from 5 pattern in Synchronisiii With Said Iiieiiiory readout one another, 4 so that when each of said Msectors is 'read the beam each sector having a sector synchronization pulse re- 1S deected to a dicernt pofsmon Within Said Patirii corded in a position corresponding to the beginning the pattein rpeatmg itself@ response to each Origin of Said Sector 7 snchrogizlaton 1pulse received. i the first sector having an origin synchronization pulse Sym o isp ay apparatus for Converting input codes to displayed symbols corresponding thereto comprising:

a memory device comprising a plurality of M sectors,

M being the number -of bits of information representing each of said symbols,

resenting one symbol; each sector storing N bits of information, N being the a cathode ray tube having a face and an electron beam number of symbols to be generated,

that scans a predetermined portion of said face in the bits of information of said symbols being stored in vertical and horizontal directions in a scanning time Said memory device so that all bits representing each interval substantially equal to said predetermined Syriiboi are Stored (N-i) PoSitionS apart from 011e time interval; and another synchronizing means for synchronizing the scan of said each Sector having a Sector syneiironilation PuiSe reelectron beam with the origin synchronization pulse Cordefi in a Position corresponding i0 the beginning and the sector synchronization pulses so that bits hof Said Sector from each of said sectors determine blanking or iint e rst secior having an Origin Syilchromzauon. puise blanking of said beam at different predetermined recorfied m a position corresponding to the beginning beam positions on said portion of the face of said :of ald. first Sector tube the bits in all sectors having clock pulses recorded in positions Corresponding thereto;

Simi synchronizing mea?? Comprising Wuming means means for reading from said memory device in a preifiggeied 'by Said Origin synchronization puise and 70 determined time interval, M bits of information repsaid sector synchronization pulses for controlling resenting one Symbol and producing pulses in acscanning of said electron beam in a predetermined Cordan therewith;

Pattern in SyneiironiSrn With merriory readout S0 that a cathode ray tube having a face and an electron beam when each of said M sectors is read the beam is defor displaying said symbols on said face at predeflected to a different position within said pattern, the termined primary positions;

symbol position generating means for deflecting said electron beam to said primary positions,

said symbol position generating means being energized by said origin synchronization pulse to deflect said beam to another primary position in response to each origin synchronization pulse received thereby;

synchronizing means for synchronizing the scan of said electron beam with each origin synchronization pulse and with the sector synchronization pulses so that bits of information from each of said sectors representing a single symbol relate to different predetermined beam secondary positions associated With said primary position of the face of said tube,

said synchronizing means comprising counting means triggered by said origin synchronization pulse and said sector synchronization pulses for controlling scanning of said electron beam in a predetermined pattern in synchronism with said memory readout so that when each of said M sectors is read the beam is deflected to a different position Within said pattern, the pattern repeating itself in response to each origin `synchronization pulse received;

counter means energized by input codes representing a single symbol, `by said origin synchronization pulse and by said clock pulses for producing pulses when the energizing clock pulses correspond in time to the bits of information of said single symbol stored in said sectors; and

gating means energized by the pulses produced by said counter means and said -reading means and by said sector synchronization pulse for controlling blanking or unblankin-g of said electron beam in accordance with the M pulses supplied by said reading means so that the beam is blanked or unblanked at each of the secondary positions within said scanning pattern, thereby displaying said symbol in accordance with said input codes.

8. A symbol display apparatus for converting input codes to displayed symbols corresponding thereto cornprising:

a memory device comprising a plurality of M sectors,

M being the number of bits of information representing each of said symbols,

each sector storing N bits of information, N being the number of symbols to be generated,

the bits of information of said symbols being stored in said memory device so that all bits representing each symbol are stor-ed (N-1) positions apart from one another,

each sector having a sector synchronization pulse recorded in a position corresponding to the beginning of said sector,

the Iirst sector having an origin synchronization pulse recorded in a position corresponding to the beginning of said first sector,

the bits in al1 sectors having clock pulses recorded in positions corresponding thereto;

means for reading from said memory device, in a predetermined time interval, M bits of information representing one symbol and producing pulses in accordance therewith;

a vcathode ray tube having a face and an electron beam for displaying said symbols on said face at predetermined primary positions;

symbol position generating means for deecting said electron beam to said primary positions,

said symbol position generating means being energized by said origin :synchronization p-ulse to deflect said beam to another primary position in response to each origin synchronization pulse received thereby;

synchronizing means for synchronizing the scan of said electron Vbeam with each origin synchronization pulse and with the sector synchronization pulses so that bits of information from each of said sect-ors representing a single symbol relate to different predetermined beam secondary positions associated Witih said primary position ofthe face of said tube,

said synchronizing means comprising counting means triggered by said origin synchronization pulse and said sector synchronization pulses for controlling scanning of said electron beam in a predetermined pattern in synchronism With said memory readout so that when each of said M sectors is read the beam is deflected to a different secondary position Within said pattern, the pattern repeating itself in response to each origin synchronization pulse received;

binary counting means for counting down from (N-l) to zero and producing a .pulse at zero,

said binary counting means being operable to count from numbers set therein corresponding to said input codes and actuated by said -origin synchronization pulse and by said clock pulses; and

gating means energized by the pulses produced by said counter means and said reading means and by said sector synchronization pulse for controlling blanking or unblanking of said electron beam in accordance with the M pulses supplied by said reading means so that the beam is |blanked or -unblanked at each of the secondary positions Within said .scanning pattern, thereby displaying said symbol in accordance With said input codes.

9. A symbol display apparatus for converting input codes to displayed symbols corresponding thereto comprising:

a memory device comprising a plurality of M sectors,

M being the number of bits of information representing each of said symbols,

each sector storing N bits of information, N being the number of symbols to be generated,

the bits of information of said symbols being stored in said memory -device so that all bits representing each symbol are stored (N-l) positions apart from one another,

each sector having a sector synchronization pulse recorded in a position corresponding to the beginning of said sector,

the first sector having an origin synchronization pulse recorded `in a position corresponding to the beginning of said first sector,

the bits in all sectors having clock pulses recorded in positions corresponding thereto;

means for reading from said memory device, in a predetermined time interval, M bits of information representing one symbol and producing pulses in accordance therewith;

a cathode ray tube having `a face and an electron beam for displaying said symbols on said face at predetermined primary positions;

symbol position generating means for deflecting said electron beam to said primary positions,

said symbol position generating lmeans being energized by said origin synchronization pulse to deflect said beam to another primary position in response to each origin synchronization pulse received thereby;

synchronizing means for synchronizing the scan of said electron beam with each :origin synchronization pulse and With the sector synchronization pulses so that bits of information fnom each of said sectors representing a single symbol relate to different predetermined beam secondary positions associated with said primary position of the face of said tube,

said synchronizing means comprising counting means triggered by said origin synchronization pulse and said sector synchronization pulses for controlling scanning of said electron beam in a predetermined pattern in synchronism With said memory readout so that when each of said M sectors is -read the beam is deflected to a different secondary position Within said pattern, the pattern repeating itself in response to each origin synchronization pulse received;

binary counting means -for counting down from (N-l) to zero and producing a pulse at zero,

said binary counting means bein-g operable to count from numbers set therein corresponding to said input codes and actuated by said origin synchronization lpulse and by said clock pulses, said :binary counting7 means being automatically resettable from zero to (N-l); and

`gating means energized by the pulses produced by said counter means and said reading means and by said sector synchronization pulse for controlling blanking Ior unblanking of said electron beam in accordance with the M pulses supplied by said reading means so that the beam is blanked or unblanked at each of the secondary positions Within said scanning pattern, thereby displaying said symbol in accordance with said input codes.

l0. Apparatus responsive to an input code identifying a symbol for displaying that symbol, said apparatus comprising:

a cathode ray tube including means for generating an electron beam;

deflection means for deecting said beam to cause it to describe a matrix of display points;

a memory comprising a movable recording medium References Cited by the Examiner UNITED STATES PATENTS 2,679,035 5/1954 Daniels et al 340-165 2,923,922 2/1960 Blickensderfer 340-174 3,060,414 10/1962 Dirks 340-1741 3,103,658 9/1963 Chiang 340-3241 3,175,208 3/1965 Simmons S40-324.1 3,226,706 l2/l965 Artzt 340-3241 NEIL C. READ, Primary Examiner.

THOMAS B. HABECKER, Examiner.

A. I. KASPER, Assistant Examiner. 

10. APPARATUS RESPONSIVE TO AN INPUT CODE IDENTIFYING A SYMBOL FOR DISPLAYING THAT SYMBOL, SAID APPARATUS COMPRISING: A CATHODE RAY TUBE INCLUDING MEANS FOR GENERATING AN ELECTRON BEAM; DEFLECTION MEANS FOR DEFLECTING SAID BEAM TO CAUSE IT TO DESCRIBE A MATRIX OF DISPLAY POINTS; A MEMORY COMPRISING A MOVABLE RECORDING MEDIUM DEFINING A PLURALITY OF SECTORS EQUAL TO THE NUMBER OF POINTS IN SAID MATRIX, EACH OF SAID SECTORS INCLUDING A PLURALITY OF BIT POSITIONS EQUAL TO THE NUMBER OF DIFFERENT SYMBOLS TO BE DISPLAYED; MEANS SYNCHRONIZED WITH SAID DEFLECTION MEANS AND RESPONSIVE TO SAID INPUT CODE FOR SEQUENTIALLY READING A CORRESPONDINGLY POSITIONED BIT FROM EACH OF SAID SECTORS; AND INTENSITY CONTROL MEANS RESPONSIVE TO SAID BITS READ FROM SAID MEMORY FOR CONTROLLING THE INTENSITY OF SAID BEAM. 